net-snmp: disable install parallelism

Without the change install phase fails as:

installing
install flags: -j16 ...
...
./.libs/libnetsnmpagent.so: file not recognized: file format not recognized
collect2: error: ld returned 1 exit status
make[1]: *** [Makefile:1012: libnetsnmpmibs.la] Error 1
make[1]: *** Waiting for unfinished jobs....

pkgs/servers/monitoring/net-snmp/default.nix

···
     ++ lib.optional withPerlTools perlWithPkgs;
 
   enableParallelBuilding = true;
+  # Missing dependencies during relinking:
+  #   ./.libs/libnetsnmpagent.so: file not recognized: file format not recognized
+  enableParallelInstalling = false;
   doCheck = false;  # tries to use networking
 
   postInstall = ''